[u/mrichter/AliRoot.git] / ITS / AliITSVertexerZ.cxx

/**************************************************************************
 * Copyright(c) 1998-2003, ALICE Experiment at CERN, All rights reserved. *
 *                                                                        *
 * Author: The ALICE Off-line Project.                                    *
 * Contributors are mentioned in the code where appropriate.              *
 *                                                                        *
 * Permission to use, copy, modify and distribute this software and its   *
 * documentation strictly for non-commercial purposes is hereby granted   *
 * without fee, provided that the above copyright notice appears in all   *
 * copies and that both the copyright notice and this permission notice   *
 * appear in the supporting documentation. The authors make no claims     *
 * about the suitability of this software for any purpose. It is          *
 * provided "as is" without express or implied warranty.                  *
 **************************************************************************/
#include "AliITSVertexerZ.h"
#include<TBranch.h>
#include<TClonesArray.h>
#include<TH1.h>
#include <TString.h>
#include<TTree.h>
#include "AliESDVertex.h"
#include "AliITSgeomTGeo.h"
#include "AliITSRecPoint.h"
#include "AliITSRecPointContainer.h"
#include "AliITSZPoint.h"

/////////////////////////////////////////////////////////////////
// this class implements a fast method to determine
// the Z coordinate of the primary vertex
// for p-p collisions it seems to give comparable or better results
// with respect to what obtained with AliITSVertexerPPZ
// It can be used successfully with Pb-Pb collisions
////////////////////////////////////////////////////////////////

ClassImp(AliITSVertexerZ)


//______________________________________________________________________
AliITSVertexerZ::AliITSVertexerZ():AliITSVertexer(),
fFirstL1(0),
fLastL1(0),
fFirstL2(0),
fLastL2(0),
fDiffPhiMax(0),
fZFound(0),
fZsig(0.),
fZCombc(0),
fLowLim(0.),
fHighLim(0.),
fStepCoarse(0),
fTolerance(0.),
fMaxIter(0),
fWindowWidth(0) {
  // Default constructor
  SetDiffPhiMax();
  SetFirstLayerModules();
  SetSecondLayerModules();
  SetLowLimit();
  SetHighLimit();
  SetBinWidthCoarse();
  SetTolerance();
  SetPPsetting();
  ConfigIterations();
  SetWindowWidth();
}

//______________________________________________________________________
AliITSVertexerZ::AliITSVertexerZ(Float_t x0, Float_t y0):AliITSVertexer(),
fFirstL1(0),
fLastL1(0),
fFirstL2(0),
fLastL2(0),
fDiffPhiMax(0),
fZFound(0),
fZsig(0.),
fZCombc(0),
fLowLim(0.),
fHighLim(0.),
fStepCoarse(0),
fTolerance(0.),
fMaxIter(0),
fWindowWidth(0) {
  // Standard Constructor
  SetDiffPhiMax();
  SetFirstLayerModules();
  SetSecondLayerModules();
  SetLowLimit();
  SetHighLimit();
  SetBinWidthCoarse();
  SetTolerance();
  SetPPsetting();
  ConfigIterations();
  SetWindowWidth();
  SetVtxStart((Double_t)x0,(Double_t)y0,0.);

}

//______________________________________________________________________
AliITSVertexerZ::~AliITSVertexerZ() {
  // Destructor
  delete fZCombc;
}

//______________________________________________________________________
void AliITSVertexerZ::ConfigIterations(Int_t noiter,Float_t *ptr){
  // configure the iterative procedure to gain efficiency for
  // pp events with very low multiplicity
  Float_t defaults[5]={0.02,0.05,0.1,0.2,0.3};
  fMaxIter=noiter;
  if(noiter>5){
    Error("ConfigIterations","Maximum number of iterations is 5\n");
    fMaxIter=5;
  }
  for(Int_t j=0;j<5;j++)fPhiDiffIter[j]=defaults[j];
  if(ptr)for(Int_t j=0;j<fMaxIter;j++)fPhiDiffIter[j]=ptr[j];
}

//______________________________________________________________________
Int_t AliITSVertexerZ::GetPeakRegion(TH1F*h, Int_t &binmin, Int_t &binmax){
  // Finds a region around a peak in the Z histogram
  // Case of 2 peaks is treated 
  Int_t imax=h->GetNbinsX();
  Float_t maxval=0;
  Int_t bi1=h->GetMaximumBin();
  Int_t bi2=0;
  for(Int_t i=imax;i>=1;i--){
    if(h->GetBinContent(i)>maxval){
      maxval=h->GetBinContent(i);
      bi2=i;
    }
  }
  Int_t npeaks=0;

  if(bi1==bi2){
    binmin=bi1-3;
    binmax=bi1+3;
    npeaks=1;
  }else{
    TH1F *copy = new TH1F(*h);
    copy->SetBinContent(bi1,0.);
    copy->SetBinContent(bi2,0.);
    Int_t l1=TMath::Max(bi1-3,1);
    Int_t l2=TMath::Min(bi1+3,h->GetNbinsX());
    Float_t cont1=copy->Integral(l1,l2);
    Int_t ll1=TMath::Max(bi2-3,1);
    Int_t ll2=TMath::Min(bi2+3,h->GetNbinsX());
    Float_t cont2=copy->Integral(ll1,ll2);
    if(cont1>cont2){
      binmin=l1;
      binmax=l2;
      npeaks=1;
    }
    if(cont2>cont1){
      binmin=ll1;
      binmax=ll2;
      npeaks=1;
    }
    if(cont1==cont2){
      binmin=l1;
      binmax=ll2;
      if(bi2-bi1==1) npeaks=1;
      else npeaks=2;
    }  
    delete copy;
  }    
  return npeaks;
}
//______________________________________________________________________
AliESDVertex* AliITSVertexerZ::FindVertexForCurrentEvent(TTree *itsClusterTree){
  // Defines the AliESDVertex for the current event
  VertexZFinder(itsClusterTree);
  Int_t ntrackl=0;
  for(Int_t iteraz=0;iteraz<fMaxIter;iteraz++){
    if(fCurrentVertex) ntrackl=fCurrentVertex->GetNContributors();
    if(!fCurrentVertex || ntrackl==0 || ntrackl==-1){
      Float_t diffPhiMaxOrig=fDiffPhiMax;
      fDiffPhiMax=GetPhiMaxIter(iteraz);
      VertexZFinder(itsClusterTree);
      fDiffPhiMax=diffPhiMaxOrig;
    }
  }
  if(fComputeMultiplicity) FindMultiplicity(itsClusterTree);
  return fCurrentVertex;
}  

//______________________________________________________________________
void AliITSVertexerZ::VertexZFinder(TTree *itsClusterTree){
  // Defines the AliESDVertex for the current event
  fCurrentVertex = 0;
  Double_t startPos[3]={GetNominalPos()[0],GetNominalPos()[1],GetNominalPos()[2]};
  Double_t startCov[6]={GetNominalCov()[0],GetNominalCov()[1],GetNominalCov()[2],
			GetNominalCov()[3],GetNominalCov()[4],GetNominalCov()[5]};
  ResetVertex();
  TClonesArray *itsRec  = 0;
  // lc1 and gc1 are local and global coordinates for layer 1
  Float_t gc1[3]={0.,0.,0.}; // ; for(Int_t ii=0; ii<3; ii++) gc1[ii]=0.;
  // lc2 and gc2 are local and global coordinates for layer 2
  Float_t gc2[3]={0.,0.,0.}; //; for(Int_t ii=0; ii<3; ii++) gc2[ii]=0.;
  AliITSRecPointContainer* rpcont=AliITSRecPointContainer::Instance();
  itsRec=rpcont->FetchClusters(0,itsClusterTree);
  if(!rpcont->IsSPDActive()){
    AliWarning("Null pointer for RecPoints branch, vertex not calculated");
    ResetHistograms();
    fCurrentVertex = new AliESDVertex(startPos,startCov,99999.,-2);
    return;
  }

  Int_t nrpL1 = 0;
  Int_t nrpL2 = 0;
  nrpL1=rpcont->GetNClustersInLayerFast(1);
  nrpL2=rpcont->GetNClustersInLayerFast(2);

  if(nrpL1 == 0 || nrpL2 == 0){
    AliDebug(1,Form("No RecPoints in at least one SPD layer (%d %d)",nrpL1,nrpL2));
    ResetHistograms();
    fCurrentVertex = new AliESDVertex(startPos,startCov,99999.,-2);
    return;
  }
  // Force a coarse bin size of 200 microns if the number of clusters on layer 2
  // is low
  if(nrpL2<fPPsetting[0])SetBinWidthCoarse(fPPsetting[1]);
  // By default nbincoarse=(10+10)/0.01=2000
  Int_t nbincoarse = static_cast<Int_t>((fHighLim-fLowLim)/fStepCoarse);
  if(fZCombc)delete fZCombc;
  fZCombc = new TH1F("fZCombc","Z",nbincoarse,fLowLim,fLowLim+nbincoarse*fStepCoarse);

 /* Test the ffect of mutiple scatternig on error. Negligible
  // Multiple scattering
  Float_t beta=1.,pmed=0.875; //pmed=875 MeV (for tracks with dphi<0.01 rad)
  Float_t beta2=beta*beta;
  Float_t p2=pmed*pmed;
  Float_t rBP=3; //Beam Pipe radius = 3cm
  Float_t dBP=0.08/35.3; // 800 um of Be
  Float_t dL1=0.01; //approx. 1% of radiation length  
  Float_t theta2BP=14.1*14.1/(beta2*p2*1e6)*TMath::Abs(dBP);
  Float_t theta2L1=14.1*14.1/(beta2*p2*1e6)*TMath::Abs(dL1);
*/
  Int_t nEntriesMod[kNSPDMod];
  TClonesArray* recpArr[kNSPDMod];
  for(Int_t modul=0; modul<kNSPDMod; ++modul) {
    if(!fUseModule[modul]) {
      nEntriesMod[modul]=0;
      recpArr[modul]=0;
    } else {
      recpArr[modul]=rpcont->UncheckedGetClusters(modul);
      nEntriesMod[modul]=recpArr[modul]->GetEntriesFast();
    }
  }
      
  Int_t maxdim=TMath::Min(nrpL1*nrpL2,50000);  // temporary; to limit the size in PbPb
  static TClonesArray points("AliITSZPoint",maxdim);
  Int_t nopoints =0;
  for(Int_t modul1= fFirstL1; modul1<=fLastL1;modul1++){   // Loop on modules of layer 1
    if(!fUseModule[modul1]) continue;
    UShort_t ladder=int(modul1/4)+1;  // ladders are numbered starting from 1
    TClonesArray *prpl1=recpArr[modul1]; //rpcont->UncheckedGetClusters(modul1);
    Int_t nrecp1 = nEntriesMod[modul1]; //prpl1->GetEntries();
    for(Int_t j1=0;j1<nrecp1;j1++){
      AliITSRecPoint *recp1 = (AliITSRecPoint*)prpl1->At(j1);
      recp1->GetGlobalXYZ(gc1);
      gc1[0]-=GetNominalPos()[0]; // Possible beam offset in the bending plane
      gc1[1]-=GetNominalPos()[1]; //   "               "
      Float_t phi1 = TMath::ATan2(gc1[1],gc1[0]);
      if(phi1<0)phi1+=TMath::TwoPi();
      for(Int_t ladl2=0 ; ladl2<fLadOnLay2*2+1;ladl2++){
	for(Int_t k=0;k<4;k++){
 	  Int_t ladmod=fLadders[ladder-1]+ladl2;
	  if(ladmod>AliITSgeomTGeo::GetNLadders(2)) ladmod=ladmod-AliITSgeomTGeo::GetNLadders(2);
	  Int_t modul2=AliITSgeomTGeo::GetModuleIndex(2,ladmod,k+1);
	  if(modul2<0)continue;
	  if(!fUseModule[modul2]) continue;
	  itsRec=recpArr[modul2]; // rpcont->UncheckedGetClusters(modul2);
	  Int_t nrecp2 = nEntriesMod[modul2]; // itsRec->GetEntries();
	  for(Int_t j2=0;j2<nrecp2;j2++){
	    AliITSRecPoint *recp2 = (AliITSRecPoint*)itsRec->At(j2);
	    recp2->GetGlobalXYZ(gc2);
	    gc2[0]-=GetNominalPos()[0];
	    gc2[1]-=GetNominalPos()[1];
	    Float_t phi2 = TMath::ATan2(gc2[1],gc2[0]);
	    if(phi2<0)phi2+=TMath::TwoPi();

	    Float_t diff = TMath::Abs(phi2-phi1); 
	    if(diff>TMath::Pi())diff=TMath::TwoPi()-diff;
	    if(diff<fDiffPhiMax){
	      Float_t r1=TMath::Sqrt(gc1[0]*gc1[0]+gc1[1]*gc1[1]);
	      Float_t zc1=gc1[2];
	      Float_t erz1=recp1->GetSigmaZ2();
	      Float_t r2=TMath::Sqrt(gc2[0]*gc2[0]+gc2[1]*gc2[1]);
	      Float_t zc2=gc2[2];
	      Float_t erz2=recp2->GetSigmaZ2();
	      //	Float_t tgth=(zc2[j]-zc1[i])/(r2-r1); // slope (used for multiple scattering)
	      Float_t zr0=(r2*zc1-r1*zc2)/(r2-r1); //Z @ null radius
	      Float_t ezr0q=(r2*r2*erz1+r1*r1*erz2)/((r2-r1)*(r2-r1)); //error on Z @ null radius
	      /*
	      // Multiple scattering
	      ezr0q+=r1*r1*(1+tgth*tgth)*theta2L1/2; // multiple scattering in layer 1
	      ezr0q+=rBP*rBP*(1+tgth*tgth)*theta2BP/2; // multiple scattering in beam pipe
	      */
	      if(nopoints<maxdim) new(points[nopoints++])AliITSZPoint(zr0,ezr0q);	      
	      fZCombc->Fill(zr0);
	    }
	  }
	}
      }
    }
  }

  points.Sort();

  Double_t contents = fZCombc->GetEntries()- fZCombc->GetBinContent(0)-fZCombc->GetBinContent(nbincoarse+1);
  if(contents<1.){
    //    Warning("FindVertexForCurrentEvent","Insufficient number of rec. points\n");
    ResetHistograms();
    fCurrentVertex = new AliESDVertex(startPos,startCov,99999.,-1);
    points.Clear();
    return;
  }

  TH1F *hc = fZCombc;

  
  if(hc->GetBinContent(hc->GetMaximumBin())<3)hc->Rebin(4);
  Int_t binmin,binmax;
  Int_t nPeaks=GetPeakRegion(hc,binmin,binmax);   
  if(nPeaks==2)AliDebug(2,"2 peaks found");
  Float_t zm =0.;
  Float_t ezm =0.;
  Float_t lim1 = hc->GetBinLowEdge(binmin);
  Float_t lim2 = hc->GetBinLowEdge(binmax)+hc->GetBinWidth(binmax);
  Float_t widthSR=lim2-lim1;

  if(nPeaks ==1 && (lim2-lim1)<fWindowWidth){
    Float_t c=(lim1+lim2)/2.;
    lim1=c-fWindowWidth/2.;
    lim2=c+fWindowWidth/2.;
  }
  Int_t niter = 0, ncontr=0;
  do {
    // symmetrization
    if(zm  !=0.){
      Float_t semilarg=TMath::Min((lim2-zm),(zm-lim1));
      lim1=zm - semilarg;
      lim2=zm + semilarg;
    }

    zm=0.;
    ezm=0.;
    ncontr=0;
    for(Int_t i =0; i<points.GetEntries(); i++){
      AliITSZPoint* p=(AliITSZPoint*)points.UncheckedAt(i);
      if(p->GetZ()>lim1 && p->GetZ()<lim2){
        Float_t deno = p->GetErrZ();
        zm+=p->GetZ()/deno;
        ezm+=1./deno;
        ncontr++;
      }
    }
    if(ezm>0) {
      zm/=ezm;
      ezm=TMath::Sqrt(1./ezm);
    }
    niter++;
  } while(niter<10 && TMath::Abs((zm-lim1)-(lim2-zm))>fTolerance);
  if(nPeaks==2) ezm=widthSR;
  Double_t position[3]={GetNominalPos()[0],GetNominalPos()[1],zm};
  Double_t covmatrix[6]={GetNominalCov()[0],0.,GetNominalCov()[2],0.,0.,ezm};
  fCurrentVertex = new AliESDVertex(position,covmatrix,99999.,ncontr);
  fCurrentVertex->SetTitle("vertexer: Z");
  fCurrentVertex->SetDispersion(fDiffPhiMax);
  fNoVertices=1;
  points.Clear();
  if(ncontr>fMinTrackletsForPilup){ 
    Float_t secPeakPos;
    Int_t ncontr2=FindSecondPeak(fZCombc,binmin,binmax,secPeakPos);
    if(ncontr2>=fMinTrackletsForPilup){ 
      fIsPileup=kTRUE;
      fNoVertices=2;
      fZpuv=secPeakPos;
      fNTrpuv=ncontr2;
      AliESDVertex secondVert(secPeakPos,0.1,ncontr2);
      fVertArray = new AliESDVertex[2];
      fVertArray[0]=(*fCurrentVertex);
      fVertArray[1]=secondVert;
    }
  }
  if(fNoVertices==1){
    fVertArray = new AliESDVertex[1];
    fVertArray[0]=(*fCurrentVertex);	  
  }
  
  ResetHistograms();
  return;
}

//_____________________________________________________________________
Int_t AliITSVertexerZ::FindSecondPeak(TH1F* h, Int_t binmin,Int_t binmax, Float_t& secPeakPos){  
  for(Int_t i=binmin-1;i<=binmax+1;i++){
    h->SetBinContent(i,0.);
  }
  Int_t secPeakBin=h->GetMaximumBin();
  secPeakPos=h->GetBinCenter(secPeakBin);
  Int_t secPeakCont=(Int_t)h->GetBinContent(secPeakBin);
  secPeakCont+=(Int_t)h->GetBinContent(secPeakBin-1);
  secPeakCont+=(Int_t)h->GetBinContent(secPeakBin+1);  
  secPeakCont+=(Int_t)h->GetBinContent(secPeakBin-2);
  secPeakCont+=(Int_t)h->GetBinContent(secPeakBin+2);  
  return secPeakCont;
}

//_____________________________________________________________________
void AliITSVertexerZ::ResetHistograms(){
  // delete TH1 data members
  if(fZCombc)delete fZCombc;
  fZCombc = 0;
}

//________________________________________________________
void AliITSVertexerZ::PrintStatus() const {
  // Print current status
  cout <<"=======================================================\n";
  cout <<" First layer first and last modules: "<<fFirstL1<<", ";
  cout <<fLastL1<<endl;
  cout <<" Second layer first and last modules: "<<fFirstL2<<", ";
  cout <<fLastL2<<endl;
  cout <<" Max Phi difference: "<<fDiffPhiMax<<endl;
  cout <<"Limits for Z histograms: "<<fLowLim<<"; "<<fHighLim<<endl;
  cout <<"Bin sizes for coarse z histos "<<fStepCoarse<<endl;
  cout <<" Current Z "<<fZFound<<"; Z sig "<<fZsig<<endl;
  if(fZCombc){
    cout<<"fZCombc exists - entries="<<fZCombc->GetEntries()<<endl;
  }
  else{
    cout<<"fZCombc does not exist\n";
  }
 
  cout <<"=======================================================\n";
}
Commit	Line	Data
	1	/**************************************************************************
	2	* Copyright(c) 1998-2003, ALICE Experiment at CERN, All rights reserved. *
	3	* *
	4	* Author: The ALICE Off-line Project. *
	5	* Contributors are mentioned in the code where appropriate. *
	6	* *
	7	* Permission to use, copy, modify and distribute this software and its *
	8	* documentation strictly for non-commercial purposes is hereby granted *
	9	* without fee, provided that the above copyright notice appears in all *
	10	* copies and that both the copyright notice and this permission notice *
	11	* appear in the supporting documentation. The authors make no claims *
	12	* about the suitability of this software for any purpose. It is *
	13	* provided "as is" without express or implied warranty. *
	14	**************************************************************************/
	15	#include "AliITSVertexerZ.h"
	16	#include<TBranch.h>
	17	#include<TClonesArray.h>
	18	#include<TH1.h>
	19	#include <TString.h>
	20	#include<TTree.h>
	21	#include "AliESDVertex.h"
	22	#include "AliITSgeomTGeo.h"
	23	#include "AliITSRecPoint.h"
	24	#include "AliITSRecPointContainer.h"
	25	#include "AliITSZPoint.h"
	26
	27	/////////////////////////////////////////////////////////////////
	28	// this class implements a fast method to determine
	29	// the Z coordinate of the primary vertex
	30	// for p-p collisions it seems to give comparable or better results
	31	// with respect to what obtained with AliITSVertexerPPZ
	32	// It can be used successfully with Pb-Pb collisions
	33	////////////////////////////////////////////////////////////////
	34
	35	ClassImp(AliITSVertexerZ)
	36
	37
	38
	39	//______________________________________________________________________
	40	AliITSVertexerZ::AliITSVertexerZ():AliITSVertexer(),
	41	fFirstL1(0),
	42	fLastL1(0),
	43	fFirstL2(0),
	44	fLastL2(0),
	45	fDiffPhiMax(0),
	46	fZFound(0),
	47	fZsig(0.),
	48	fZCombc(0),
	49	fLowLim(0.),
	50	fHighLim(0.),
	51	fStepCoarse(0),
	52	fTolerance(0.),
	53	fMaxIter(0),
	54	fWindowWidth(0) {
	55	// Default constructor
	56	SetDiffPhiMax();
	57	SetFirstLayerModules();
	58	SetSecondLayerModules();
	59	SetLowLimit();
	60	SetHighLimit();
	61	SetBinWidthCoarse();
	62	SetTolerance();
	63	SetPPsetting();
	64	ConfigIterations();
	65	SetWindowWidth();
	66	}
	67
	68	//______________________________________________________________________
	69	AliITSVertexerZ::AliITSVertexerZ(Float_t x0, Float_t y0):AliITSVertexer(),
	70	fFirstL1(0),
	71	fLastL1(0),
	72	fFirstL2(0),
	73	fLastL2(0),
	74	fDiffPhiMax(0),
	75	fZFound(0),
	76	fZsig(0.),
	77	fZCombc(0),
	78	fLowLim(0.),
	79	fHighLim(0.),
	80	fStepCoarse(0),
	81	fTolerance(0.),
	82	fMaxIter(0),
	83	fWindowWidth(0) {
	84	// Standard Constructor
	85	SetDiffPhiMax();
	86	SetFirstLayerModules();
	87	SetSecondLayerModules();
	88	SetLowLimit();
	89	SetHighLimit();
	90	SetBinWidthCoarse();
	91	SetTolerance();
	92	SetPPsetting();
	93	ConfigIterations();
	94	SetWindowWidth();
	95	SetVtxStart((Double_t)x0,(Double_t)y0,0.);
	96
	97	}
	98
	99	//______________________________________________________________________
	100	AliITSVertexerZ::~AliITSVertexerZ() {
	101	// Destructor
	102	delete fZCombc;
	103	}
	104
	105	//______________________________________________________________________
	106	void AliITSVertexerZ::ConfigIterations(Int_t noiter,Float_t *ptr){
	107	// configure the iterative procedure to gain efficiency for
	108	// pp events with very low multiplicity
	109	Float_t defaults[5]={0.02,0.05,0.1,0.2,0.3};
	110	fMaxIter=noiter;
	111	if(noiter>5){
	112	Error("ConfigIterations","Maximum number of iterations is 5\n");
	113	fMaxIter=5;
	114	}
	115	for(Int_t j=0;j<5;j++)fPhiDiffIter[j]=defaults[j];
	116	if(ptr)for(Int_t j=0;j<fMaxIter;j++)fPhiDiffIter[j]=ptr[j];
	117	}
	118
	119	//______________________________________________________________________
	120	Int_t AliITSVertexerZ::GetPeakRegion(TH1F*h, Int_t &binmin, Int_t &binmax){
	121	// Finds a region around a peak in the Z histogram
	122	// Case of 2 peaks is treated
	123	Int_t imax=h->GetNbinsX();
	124	Float_t maxval=0;
	125	Int_t bi1=h->GetMaximumBin();
	126	Int_t bi2=0;
	127	for(Int_t i=imax;i>=1;i--){
	128	if(h->GetBinContent(i)>maxval){
	129	maxval=h->GetBinContent(i);
	130	bi2=i;
	131	}
	132	}
	133	Int_t npeaks=0;
	134
	135	if(bi1==bi2){
	136	binmin=bi1-3;
	137	binmax=bi1+3;
	138	npeaks=1;
	139	}else{
	140	TH1F copy = new TH1F(h);
	141	copy->SetBinContent(bi1,0.);
	142	copy->SetBinContent(bi2,0.);
	143	Int_t l1=TMath::Max(bi1-3,1);
	144	Int_t l2=TMath::Min(bi1+3,h->GetNbinsX());
	145	Float_t cont1=copy->Integral(l1,l2);
	146	Int_t ll1=TMath::Max(bi2-3,1);
	147	Int_t ll2=TMath::Min(bi2+3,h->GetNbinsX());
	148	Float_t cont2=copy->Integral(ll1,ll2);
	149	if(cont1>cont2){
	150	binmin=l1;
	151	binmax=l2;
	152	npeaks=1;
	153	}
	154	if(cont2>cont1){
	155	binmin=ll1;
	156	binmax=ll2;
	157	npeaks=1;
	158	}
	159	if(cont1==cont2){
	160	binmin=l1;
	161	binmax=ll2;
	162	if(bi2-bi1==1) npeaks=1;
	163	else npeaks=2;
	164	}
	165	delete copy;
	166	}
	167	return npeaks;
	168	}
	169	//______________________________________________________________________
	170	AliESDVertex* AliITSVertexerZ::FindVertexForCurrentEvent(TTree *itsClusterTree){
	171	// Defines the AliESDVertex for the current event
	172	VertexZFinder(itsClusterTree);
	173	Int_t ntrackl=0;
	174	for(Int_t iteraz=0;iteraz<fMaxIter;iteraz++){
	175	if(fCurrentVertex) ntrackl=fCurrentVertex->GetNContributors();
	176	if(!fCurrentVertex \|\| ntrackl==0 \|\| ntrackl==-1){
	177	Float_t diffPhiMaxOrig=fDiffPhiMax;
	178	fDiffPhiMax=GetPhiMaxIter(iteraz);
	179	VertexZFinder(itsClusterTree);
	180	fDiffPhiMax=diffPhiMaxOrig;
	181	}
	182	}
	183	if(fComputeMultiplicity) FindMultiplicity(itsClusterTree);
	184	return fCurrentVertex;
	185	}
	186
	187	//______________________________________________________________________
	188	void AliITSVertexerZ::VertexZFinder(TTree *itsClusterTree){
	189	// Defines the AliESDVertex for the current event
	190	fCurrentVertex = 0;
	191	Double_t startPos[3]={GetNominalPos()[0],GetNominalPos()[1],GetNominalPos()[2]};
	192	Double_t startCov[6]={GetNominalCov()[0],GetNominalCov()[1],GetNominalCov()[2],
	193	GetNominalCov()[3],GetNominalCov()[4],GetNominalCov()[5]};
	194	ResetVertex();
	195	TClonesArray *itsRec = 0;
	196	// lc1 and gc1 are local and global coordinates for layer 1
	197	Float_t gc1[3]={0.,0.,0.}; // ; for(Int_t ii=0; ii<3; ii++) gc1[ii]=0.;
	198	// lc2 and gc2 are local and global coordinates for layer 2
	199	Float_t gc2[3]={0.,0.,0.}; //; for(Int_t ii=0; ii<3; ii++) gc2[ii]=0.;
	200	AliITSRecPointContainer* rpcont=AliITSRecPointContainer::Instance();
	201	itsRec=rpcont->FetchClusters(0,itsClusterTree);
	202	if(!rpcont->IsSPDActive()){
	203	AliWarning("Null pointer for RecPoints branch, vertex not calculated");
	204	ResetHistograms();
	205	fCurrentVertex = new AliESDVertex(startPos,startCov,99999.,-2);
	206	return;
	207	}
	208
	209	Int_t nrpL1 = 0;
	210	Int_t nrpL2 = 0;
	211	nrpL1=rpcont->GetNClustersInLayerFast(1);
	212	nrpL2=rpcont->GetNClustersInLayerFast(2);
	213
	214	if(nrpL1 == 0 \|\| nrpL2 == 0){
	215	AliDebug(1,Form("No RecPoints in at least one SPD layer (%d %d)",nrpL1,nrpL2));
	216	ResetHistograms();
	217	fCurrentVertex = new AliESDVertex(startPos,startCov,99999.,-2);
	218	return;
	219	}
	220	// Force a coarse bin size of 200 microns if the number of clusters on layer 2
	221	// is low
	222	if(nrpL2<fPPsetting[0])SetBinWidthCoarse(fPPsetting[1]);
	223	// By default nbincoarse=(10+10)/0.01=2000
	224	Int_t nbincoarse = static_cast<Int_t>((fHighLim-fLowLim)/fStepCoarse);
	225	if(fZCombc)delete fZCombc;
	226	fZCombc = new TH1F("fZCombc","Z",nbincoarse,fLowLim,fLowLim+nbincoarse*fStepCoarse);
	227
	228	/* Test the ffect of mutiple scatternig on error. Negligible
	229	// Multiple scattering
	230	Float_t beta=1.,pmed=0.875; //pmed=875 MeV (for tracks with dphi<0.01 rad)
	231	Float_t beta2=beta*beta;
	232	Float_t p2=pmed*pmed;
	233	Float_t rBP=3; //Beam Pipe radius = 3cm
	234	Float_t dBP=0.08/35.3; // 800 um of Be
	235	Float_t dL1=0.01; //approx. 1% of radiation length
	236	Float_t theta2BP=14.114.1/(beta2p21e6)TMath::Abs(dBP);
	237	Float_t theta2L1=14.114.1/(beta2p21e6)TMath::Abs(dL1);
	238	*/
	239	Int_t nEntriesMod[kNSPDMod];
	240	TClonesArray* recpArr[kNSPDMod];
	241	for(Int_t modul=0; modul<kNSPDMod; ++modul) {
	242	if(!fUseModule[modul]) {
	243	nEntriesMod[modul]=0;
	244	recpArr[modul]=0;
	245	} else {
	246	recpArr[modul]=rpcont->UncheckedGetClusters(modul);
	247	nEntriesMod[modul]=recpArr[modul]->GetEntriesFast();
	248	}
	249	}
	250
	251	Int_t maxdim=TMath::Min(nrpL1*nrpL2,50000); // temporary; to limit the size in PbPb
	252	static TClonesArray points("AliITSZPoint",maxdim);
	253	Int_t nopoints =0;
	254	for(Int_t modul1= fFirstL1; modul1<=fLastL1;modul1++){ // Loop on modules of layer 1
	255	if(!fUseModule[modul1]) continue;
	256	UShort_t ladder=int(modul1/4)+1; // ladders are numbered starting from 1
	257	TClonesArray *prpl1=recpArr[modul1]; //rpcont->UncheckedGetClusters(modul1);
	258	Int_t nrecp1 = nEntriesMod[modul1]; //prpl1->GetEntries();
	259	for(Int_t j1=0;j1<nrecp1;j1++){
	260	AliITSRecPoint recp1 = (AliITSRecPoint)prpl1->At(j1);
	261	recp1->GetGlobalXYZ(gc1);
	262	gc1[0]-=GetNominalPos()[0]; // Possible beam offset in the bending plane
	263	gc1[1]-=GetNominalPos()[1]; // " "
	264	Float_t phi1 = TMath::ATan2(gc1[1],gc1[0]);
	265	if(phi1<0)phi1+=TMath::TwoPi();
	266	for(Int_t ladl2=0 ; ladl2<fLadOnLay2*2+1;ladl2++){
	267	for(Int_t k=0;k<4;k++){
	268	Int_t ladmod=fLadders[ladder-1]+ladl2;
	269	if(ladmod>AliITSgeomTGeo::GetNLadders(2)) ladmod=ladmod-AliITSgeomTGeo::GetNLadders(2);
	270	Int_t modul2=AliITSgeomTGeo::GetModuleIndex(2,ladmod,k+1);
	271	if(modul2<0)continue;
	272	if(!fUseModule[modul2]) continue;
	273	itsRec=recpArr[modul2]; // rpcont->UncheckedGetClusters(modul2);
	274	Int_t nrecp2 = nEntriesMod[modul2]; // itsRec->GetEntries();
	275	for(Int_t j2=0;j2<nrecp2;j2++){
	276	AliITSRecPoint recp2 = (AliITSRecPoint)itsRec->At(j2);
	277	recp2->GetGlobalXYZ(gc2);
	278	gc2[0]-=GetNominalPos()[0];
	279	gc2[1]-=GetNominalPos()[1];
	280	Float_t phi2 = TMath::ATan2(gc2[1],gc2[0]);
	281	if(phi2<0)phi2+=TMath::TwoPi();
	282
	283	Float_t diff = TMath::Abs(phi2-phi1);
	284	if(diff>TMath::Pi())diff=TMath::TwoPi()-diff;
	285	if(diff<fDiffPhiMax){
	286	Float_t r1=TMath::Sqrt(gc1[0]gc1[0]+gc1[1]gc1[1]);
	287	Float_t zc1=gc1[2];
	288	Float_t erz1=recp1->GetSigmaZ2();
	289	Float_t r2=TMath::Sqrt(gc2[0]gc2[0]+gc2[1]gc2[1]);
	290	Float_t zc2=gc2[2];
	291	Float_t erz2=recp2->GetSigmaZ2();
	292	// Float_t tgth=(zc2[j]-zc1[i])/(r2-r1); // slope (used for multiple scattering)
	293	Float_t zr0=(r2zc1-r1zc2)/(r2-r1); //Z @ null radius
	294	Float_t ezr0q=(r2r2erz1+r1r1erz2)/((r2-r1)*(r2-r1)); //error on Z @ null radius
	295	/*
	296	// Multiple scattering
	297	ezr0q+=r1r1(1+tgthtgth)theta2L1/2; // multiple scattering in layer 1
	298	ezr0q+=rBPrBP(1+tgthtgth)theta2BP/2; // multiple scattering in beam pipe
	299	*/
	300	if(nopoints<maxdim) new(points[nopoints++])AliITSZPoint(zr0,ezr0q);
	301	fZCombc->Fill(zr0);
	302	}
	303	}
	304	}
	305	}
	306	}
	307	}
	308
	309	points.Sort();
	310
	311	Double_t contents = fZCombc->GetEntries()- fZCombc->GetBinContent(0)-fZCombc->GetBinContent(nbincoarse+1);
	312	if(contents<1.){
	313	// Warning("FindVertexForCurrentEvent","Insufficient number of rec. points\n");
	314	ResetHistograms();
	315	fCurrentVertex = new AliESDVertex(startPos,startCov,99999.,-1);
	316	points.Clear();
	317	return;
	318	}
	319
	320	TH1F *hc = fZCombc;
	321
	322
	323	if(hc->GetBinContent(hc->GetMaximumBin())<3)hc->Rebin(4);
	324	Int_t binmin,binmax;
	325	Int_t nPeaks=GetPeakRegion(hc,binmin,binmax);
	326	if(nPeaks==2)AliDebug(2,"2 peaks found");
	327	Float_t zm =0.;
	328	Float_t ezm =0.;
	329	Float_t lim1 = hc->GetBinLowEdge(binmin);
	330	Float_t lim2 = hc->GetBinLowEdge(binmax)+hc->GetBinWidth(binmax);
	331	Float_t widthSR=lim2-lim1;
	332
	333	if(nPeaks ==1 && (lim2-lim1)<fWindowWidth){
	334	Float_t c=(lim1+lim2)/2.;
	335	lim1=c-fWindowWidth/2.;
	336	lim2=c+fWindowWidth/2.;
	337	}
	338	Int_t niter = 0, ncontr=0;
	339	do {
	340	// symmetrization
	341	if(zm !=0.){
	342	Float_t semilarg=TMath::Min((lim2-zm),(zm-lim1));
	343	lim1=zm - semilarg;
	344	lim2=zm + semilarg;
	345	}
	346
	347	zm=0.;
	348	ezm=0.;
	349	ncontr=0;
	350	for(Int_t i =0; i<points.GetEntries(); i++){
	351	AliITSZPoint* p=(AliITSZPoint*)points.UncheckedAt(i);
	352	if(p->GetZ()>lim1 && p->GetZ()<lim2){
	353	Float_t deno = p->GetErrZ();
	354	zm+=p->GetZ()/deno;
	355	ezm+=1./deno;
	356	ncontr++;
	357	}
	358	}
	359	if(ezm>0) {
	360	zm/=ezm;
	361	ezm=TMath::Sqrt(1./ezm);
	362	}
	363	niter++;
	364	} while(niter<10 && TMath::Abs((zm-lim1)-(lim2-zm))>fTolerance);
	365	if(nPeaks==2) ezm=widthSR;
	366	Double_t position[3]={GetNominalPos()[0],GetNominalPos()[1],zm};
	367	Double_t covmatrix[6]={GetNominalCov()[0],0.,GetNominalCov()[2],0.,0.,ezm};
	368	fCurrentVertex = new AliESDVertex(position,covmatrix,99999.,ncontr);
	369	fCurrentVertex->SetTitle("vertexer: Z");
	370	fCurrentVertex->SetDispersion(fDiffPhiMax);
	371	fNoVertices=1;
	372	points.Clear();
	373	if(ncontr>fMinTrackletsForPilup){
	374	Float_t secPeakPos;
	375	Int_t ncontr2=FindSecondPeak(fZCombc,binmin,binmax,secPeakPos);
	376	if(ncontr2>=fMinTrackletsForPilup){
	377	fIsPileup=kTRUE;
	378	fNoVertices=2;
	379	fZpuv=secPeakPos;
	380	fNTrpuv=ncontr2;
	381	AliESDVertex secondVert(secPeakPos,0.1,ncontr2);
	382	fVertArray = new AliESDVertex[2];
	383	fVertArray[0]=(*fCurrentVertex);
	384	fVertArray[1]=secondVert;
	385	}
	386	}
	387	if(fNoVertices==1){
	388	fVertArray = new AliESDVertex[1];
	389	fVertArray[0]=(*fCurrentVertex);
	390	}
	391
	392	ResetHistograms();
	393	return;
	394	}
	395
	396	//_____________________________________________________________________
	397	Int_t AliITSVertexerZ::FindSecondPeak(TH1F* h, Int_t binmin,Int_t binmax, Float_t& secPeakPos){
	398	for(Int_t i=binmin-1;i<=binmax+1;i++){
	399	h->SetBinContent(i,0.);
	400	}
	401	Int_t secPeakBin=h->GetMaximumBin();
	402	secPeakPos=h->GetBinCenter(secPeakBin);
	403	Int_t secPeakCont=(Int_t)h->GetBinContent(secPeakBin);
	404	secPeakCont+=(Int_t)h->GetBinContent(secPeakBin-1);
	405	secPeakCont+=(Int_t)h->GetBinContent(secPeakBin+1);
	406	secPeakCont+=(Int_t)h->GetBinContent(secPeakBin-2);
	407	secPeakCont+=(Int_t)h->GetBinContent(secPeakBin+2);
	408	return secPeakCont;
	409	}
	410
	411	//_____________________________________________________________________
	412	void AliITSVertexerZ::ResetHistograms(){
	413	// delete TH1 data members
	414	if(fZCombc)delete fZCombc;
	415	fZCombc = 0;
	416	}
	417
	418	//________________________________________________________
	419	void AliITSVertexerZ::PrintStatus() const {
	420	// Print current status
	421	cout <<"=======================================================\n";
	422	cout <<" First layer first and last modules: "<<fFirstL1<<", ";
	423	cout <<fLastL1<<endl;
	424	cout <<" Second layer first and last modules: "<<fFirstL2<<", ";
	425	cout <<fLastL2<<endl;
	426	cout <<" Max Phi difference: "<<fDiffPhiMax<<endl;
	427	cout <<"Limits for Z histograms: "<<fLowLim<<"; "<<fHighLim<<endl;
	428	cout <<"Bin sizes for coarse z histos "<<fStepCoarse<<endl;
	429	cout <<" Current Z "<<fZFound<<"; Z sig "<<fZsig<<endl;
	430	if(fZCombc){
	431	cout<<"fZCombc exists - entries="<<fZCombc->GetEntries()<<endl;
	432	}
	433	else{
	434	cout<<"fZCombc does not exist\n";
	435	}
	436
	437	cout <<"=======================================================\n";
	438	}
	439